In the Himalayas, India and China are needling each other. Welcome to what may be the century's most important contest

Activists of Shiv Sena, a Hindu hardline group, shout slogans as they burn an effigy of China's President Hu Jintao during a protest against the Chinese government in New Delhi.

Every cold war has its proxies. In a swath of Himalayan mountains wedged between the northeast Indian state of Arunachal Pradesh and China, they can take the shape of things as mundane as the empty beer bottles and cigarette butts left behind by soldiers on patrol. Up in the mountains, the Indian and Chinese armies monitor a boundary whose line the two countries don't agree on. In certain parts of that murky borderland, the soldiers on night patrols often leave behind evidence of their presence. When relations between the two countries are good, it's litter; when the situation is tense, the...